This is a review, detailed measurements and comparison of Apple's USB-C adapter to the current and last version of Google Pixel headphone adapters. The Apple adapter costs just $9 including one day shipping for free. The Google dongle costs $12. Not that any of these are large by any stretch...
www.audiosciencereview.com
The above is a review of the apple headphone dongle, take a look.
Sure, you can compare them, but the Apple dongle has a headphone dongle and the Qutest is DAC only, with no headphone out.
Unless you intend to connect them to your home Hifi and compare them, which is doable.
No, you are not missing anything, you can compare the sound of the Apple dongle to that of the Qutest in this manner.
There is so much talk and complexity regarding listening test, and how it should be done right, in a strictly controlled manner, or else! that makes most listening test done by an amateur in a home environment not-valid.
But I don't think you care, or intend on publishing your findings.
At most, you get the wrong results, it wouldn't matter, you are just doing an experiment for the heck of it! Am I right?
Go ahead and do your experiment, it should be an eye opener and fun.
If you end up preferring the dongle to the Qutest, do two things:
- Sell me the Qutest for cheap.
- Book an appointment with a local chemist or GP, to check your hearing and possibly remove excess wax.